Within the last several years much interest has been focused upon the ways in which vertebrate rods and the pigment epithelium (PE) interact, especially with regard to the assembly, shedding and digestion of outer segment discs. However, the anatomical relationship between mammalian cones and the PE, and their interactions, remain poorly understood. In this research project our efforts are concenrated in two general areas: first, in establishing the normal ultrastructural relationship between mammalian cone outer segments (COS's) and the PE by electron microscopy; and second, in describing the changes that occur when that normal intercellular relationship is experimentally altered or disrupted. Ongoing projects include: (1) a study of the normal relationship between foveal and peripheral cones in the primate retina; (2) a study of the rhythmic cycle of disc shedding in cones and its relationship to light; (3) an examination of the ultrastructural changes that occur after experimental retinal detachment and following surgical reattachment in cats and rhesus monkeys.